It’s fun when 2 people get together and write a sequence of action about their characters. It’s even more fun when those characters have completely opposite character traits, maybe they’ll wind each other up? (which is very fun to write!) or maybe they’ll use their separate personality traits and skills to their advantage (good cop bad cop perhaps?).
In fiction there’s actually a word for a character who’s the total opposite of another, and that’s ‘foil’. Wikipedia says a foil “contrasts with another character (usually the protagonist) in order to highlight particular qualities of the other character” (see the full article here, it’s interesting).
Examples of contrasting characters
Kirk & Spock – Kirk is emotional, hot-headed, ready for action, rushes straight in without thinking. Spock is calculated, emotionless, logical, will think before taking action. He’s there to remind Kirk when he’s doing something stupid, and to provide the intelligent answers that Kirk might ask.
Lister & Rimmer from Red Dwarf – My favourite example. Lister is care-free, positive, emotional, messy, and enjoys having a laugh. His complaining bunkmate Rimmer is negative, stuck in the mud, and prefers order and routine. The two clash in the most hilarious ways.
Harry Potter & Draco Malfoy – Draco can be seen as a foil to the Harry Potter character, he’s the opposite of Harry and they make different choices; Draco eventually joins Voldemort, while Harry opposes him.
Riggs & Murtaugh in Lethal Weapon – Like many “buddy cop” movies, the main characters are opposites. One is a casual, suicidal alcoholic who doesn’t mind taking risks, the other is more serious, smart, careful, family man who just wants to get to retirement without too much fuss, his catchphrase is “I’m too old for this shit”.
Team your character up with their opposite
Think about your character in your rolpelaying game, which character would be their opposite? Now team them up for a side-mission, or perhaps get them trapped in a lift for a while and have a discussion, do they wind each other up? Do they become friends? Do they end up in a fight?